Table 2. Predictive parameters used in this study, derived from the GPS (speed) and the accelerometer sensors.
| predictor | direction | label | explanation |
| GPS speed (m s−1) | - | speed | 3D speed |
| body pitch (°) | surge | pitchX | angle of the body along the surge axis |
| heave | pitchZ | angle of the body along the heave axis | |
| body roll (°) | sway | rollY | angle of the body along the sway axis |
| maximum dynamic body acceleration (g) | surge | mdbaX | maximum dynamic body acceleration along the surge axis |
| sway | mdbaY | maximum dynamic body acceleration along the sway axis | |
| heave | mdbaZ | maximum dynamic body acceleration along the heave axis | |
| overall dynamic body acceleration (g) | surge | odbaX | Mean dynamic body acceleration along the surge axis |
| sway | odbaY | Mean dynamic body acceleration along the sway axis | |
| heave | odbaZ | Mean dynamic body acceleration along the heave axis | |
| - | odba | overall dynamic body acceleration (odbaX+odbaY+odbaZ) | |
| dominant power spectrum (g2Hz−1) | surge | dpsX | maximum power spectral density (psd) of dynamic acceleration along the surge axis |
| sway | dpsY | maximum psd along the sway axis | |
| heave | dpsZ | maximum psd along the heave axis | |
| frequency at the dominant power spectrum (Hz) | surge | fdpsX | frequency at the maximum psd along the surge axis |
| sway | fdpsY | frequency at the maximum psd along the sway axis | |
| heave | fdpsZ | frequency at the maximum psd along the heave axis |
The dominant power spectrum measures the relative amount of kinetic energy that is spent at the dominant periodicity in a signal (see Text S1 for more details).The integration interval of the measurement for the accelerometer sensor is 3 seconds with 20 Hz. The direction in which each variable is defined is given in Cartesian coordinates relative to the ground surface: surge represents the x-axis, sway the y-axis and heave the z-axis. The measurement units (SI) are provided in parentheses.